Precious Metal Blacks for the Coating of Gas Sensors

Gas sensors are essential for the highly sensitive detection of toxic gases such as carbon monoxide, chlorine, hydrogen sulphide and nitrogen oxides. By tracking the air concentration of these toxic gases, it is possible to register potential dangers to health and the environment and take timely action. Fundamentally, electrochemical gas sensors function through measuring electrode signals proportional to the gas concentration. If the electrical current reaches a critical value, a warning is displayed to signal a critical gas concentration.

Types of Gas Sensors

Among gas sensors, there are different types of sensors: sensors based on infrared light, semi-conductors, catalytic bead sensors as well as electrochemical sensors with precious metals as their key component. During the production of the precious metal containing sensors, an ink consisting of precious metal blacks mixed with additives is produced and then applied on a PTFE membrane. The applications for gas sensors are control of indoor air quality, leakage detection and emission control.

Precious metal blacks are very fine powders of precious metals with high catalytic activity and an excellent selectivity towards specific toxic gases. Precious metal blacks are in addition to their use in gas sensors also applied in the dental industry, in proton exchange membranes and in electrodes for electrochemistry.

Heraeus offers high-quality precious metal blacks at different surface areas. The available precious metal blacks are shown in the table below. Due to Heraeus’ broad portfolio, it is possible to manage costs and react to price increases of certain precious metals. For example, the recent price increase for iridium potentially lead to the need of substituting iridium blacks with other products like platinum blacks to ensure a feasible performance-cost ratio of your products.